For example, Japanese Patent Laid-Open No. 2004-80100 has proposed a color conversion processing technique for converting a local color in a displayed image into another color designated by the user by generating a color conversion table expressed by a color space in an image processing apparatus.
In the aforementioned color processing, in order to extract color information to be converted from a displayed image (to capture a color), a color capture index (e.g., a frame or the like) used to designate a range to be extracted is displayed. Using pixel information within this color capture index, a color to be used in color conversion is determined. However, if the range of this color capture index is broad (for example, if the frame is large), other colors are unwantedly extracted, and a desired color conversion effect cannot be obtained. If the range of the color capture index is narrow (for example, if the frame is small), since the number of samples of pixels decreases, it becomes difficult to specify a pixel having the same color as the extracted color, resulting in low color conversion precision.
For this reason, the range (size) of the color capture index is empirically determined to obtain desired color conversion precision.
However, when so-called digital zoom processing for enlarging an image by pixel interpolation is applied to display an image, if color extraction using the color capture index is made, the number of sampling pixels included in the index substantially decreases. For this reason, the color conversion precision drops, and a desired color conversion effect cannot often be obtained.